Tim Minchin has mocked the Turnbull government's decision to hold a non-binding postal vote on same-sex marriage in a pithy music video uploaded to his social media channels.

The Australian composer and comedian has reworked Peter Allen's classic song I Still Call Australia Home into a tune called I Still Call Australia Homophobic.

Minchin recorded the song on his iPhone and uploaded the video to Facebook on Friday morning. He said he penned the "heartfelt song to my homeland" to encourage all Australians to vote for equality.

"No matter how far or how wide I roam, I still call Australia ... homophobic," Minchin says in his song.

"It's bad enough these pollie arseholes pass discriminatory laws, now we're forced to dance the plebiscite jig. But on the upside, this plebiscite might enlighten us. At least we'll know exactly how many Aussies are bigoted c----."

The song then encourages politicians to "do their bloody jobs".

"Then Carrie can marry Sally, and Ben can bone Tone in the marriage bed in their Aussie home. So you can shove your cherry picked Bible passage up your puckered bottom. Your attempt to keep Australia in the past will be a failure because most of Australia aren't homophobic."

The video ends with a personal note from Minchin, stating he believes the plebiscite is "noxious".

"Polls show that Aussies are overwhelmingly in support o marriage equality," he said.

"Not that it should matter, it's not f---ing X-Factor. But let's drown the mofos in the 'yes' votes."